1. Field of the Invention
The present invention relates to a method of delivering DNA to neointimal cells in injured blood vessels. In particular is provided a method of decreasing or inhibiting the proliferation of neointimal cells by delivering DNA that causes the decrease or inhibition of proliferation of neointimal cells, using replication-deficient recombinant adenoviral vectors, thus treating restenosis.
2. Background Art
The smooth muscle cell (SMC) proliferation associated with arterial injury remains a major obstacle to the long-term success of coronary angioplasty. The injury activates medial SMCs, which begin to migrate and proliferate to form a neointima. Angioplasty failure rates of 25% to 50% within six months have been reported and confirmed by several authors (1-5). Previous attempts to modulate this cellular proliferation have included various mechanical and pharmacologic therapies, which have been the subject of several reviews (6-9). More recently, many efforts have been directed against various growth factors, their receptors, or cellular proto-oncogenes thought to play an important role in SMC proliferation (10-19). Although several of these methods have shown encouraging in vitro, and more recently, in vivo results, all approaches have both practical and theoretical drawbacks. Hence, while one or more of these therapeutic strategies may ultimately show clinical efficacy, the need for more powerful and specific approaches is compelling.
Gene therapeutic techniques offer the promise of efficiently transferring genes, whose products may convey therapeutic benefit, to specific groups of cells. Previous efforts to directly transduce arterial segments in vivo have used liposomal or retroviral methods to transfer marker genes into endothelial or SMCs (20-24). The feasibility of such efforts, however, has been limited by a low transfection efficiency. In in vivo models, estimates of gene transfer into arterial segments range from fewer than 1 in 10,000 cells transduced with retroviral methods (24) to fewer than 1 in 1,000 cells using liposomes.
Replication deficient recombinant adenoviral vectors have previously been shown to be efficient for transferring exogenous genes to a wide variety of cells in vivo (25-36). Such vectors can be manipulated so as to encode for recombinant gene products up to 7.5 kilobases (kb) in length (37). The recombinant virus can be propagated in certain mammalian cell lines that serve to complement the growth of replication detective adenovirus. Additionally, transduction by adenovirus, as opposed to retrovirus, does not depend on active replication of the host cell (37,38).
The present invention provides for the use of adenoviral vectors for selective and efficient expression of DNA in neointimal cells at the site of an injury. This expression can be utilized as a much needed means to treat restenosis.
The present invention provides a method of selectively expressing DNA in neointimal cells in an injured blood vessel of a subject comprising administering a replication-deficient recombinant adenovirus which functionally encodes the DNA to the blood vessel at the site of injury, such that the adenovirus remains at the site of injury for a time sufficient for the adenovirus to selectively infect neointimal cells and thereby selectively express the DNA in neointimal cells. In particular, the invention provides administering a replication-deficient recombinant adenovirus which functionally encodes a DNA encoding a protein or an antisense ribonucleic acid.
The instant invention also provides a method of treating restenosis in an injured blood vessel of a subject comprising administering to the blood vessel a replication-deficient recombinant adenovirus which functionally encodes a DNA which can decrease the proliferation of neointimal cells, such that the adenovirus remains at the site of injury for a time sufficient for the adenovirus to selectively infect and express the DNA in neointimal cells, thereby decreasing or inhibiting the proliferation of neointimal cells and treating restenosis.
Additionally, the present invention provides a method of preventing neointimal cell proliferation in an injured blood vessel of a subject comprising administering to the blood vessel a replication-deficient recombinant adenovirus which functionally encodes a DNA which can decrease the proliferation of neointimal cells, such that the adenovirus remains at the site of injury for a time sufficient for the adenovirus to selectively infect and express the DNA in neointimal cells, thereby preventing the proliferation of neointimal cells. Also provided is the use of this method of preventing neointimal cell proliferation to treat primary atherosclerosis.
The present invention further provides a method of screening DNA for the ability to inhibit proliferation of or to have cytotoxic effects on neointimal cells comprising administering to an injured blood vessel in a subject at the site of injury a replication-deficient adenovirus which functionally encodes the DNA, for a time sufficient for the adenovirus to selectively infect neointimal cells; and detecting inhibition of proliferation of or toxicity to the neointimal cells, such inhibition or toxicity indicating a DNA having the ability to inhibit proliferation of or to have cytotoxic effects on neointimal cells.